Electronic devices employ various types of input devices. One of the most popular ones is the button. A simple button provides the function of inputting a single piece of information, such as a number, a letter, or a pre-determined command.
As the functions of electronic devices multiply, simple buttons no longer meet the challenging demands. Therefore, a composite key 100 shown in FIG. 1a has been proposed. The key includes, as shown in FIG. 1b, a chassis 110, a locking device 120, a case 130, a dial 140 and a button 150. There is a hole 131 on the case 130. The locking device 120 includes an elastic component 121 and a brush 123. Screws 122 lock together the elastic component 121, the case 130, and the dial 140, which pass through the hole 131. There is a recess 141 in the center of the dial 140. The button 150 is disposed in the recess 141, and both come together with the chassis 110 to form the key 100.
Due to the locking restriction of the screws 122, the composite key 100 can only be assembled vertically. This must be taken into consideration when designing any electronic device that uses this composite key 100.
Besides, the large number of components of the composite key 100 presents a disadvantage when it comes to production cost and assembly. Therefore, the present invention discloses a mode selection apparatus with fewer components and no restriction on the assembly direction, as well as a composite key containing the mode selection apparatus.